Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

247
FXUS63 KLOT 221132
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
632 AM CDT Wed Apr 22 2026

.KEY MESSAGES...

- Isolated to perhaps widely scattered showers/storms this
  afternoon mainly across parts of northwest Indiana.

- Notably cooler near the lake today, but warming to near 80
  degrees nearly area-wide Thursday.

- More widespread showers and thunderstorms with another cold
  front very late Thursday night into Friday.

- Seasonable and dry conditions over the weekend.

&&

.DISCUSSION...
Issued at 156 AM CDT Wed Apr 22 2026

Surface observations, satellite loops, and radar data reveal a
southward-moving cold front currently near Muskegon to
Milwaukee, moving at a steady clip around 25 mph near the
land/lake interface. This boundary will likely continue to surge
down the lake prior to daybreak, and then will being to ooze
inland. After sunrise, increasing boundary layer mixing will
slow the front`s southwestward progress, initially likely
getting hung up within the first 5 miles or so of the lakefront.
This boundary will eventually get an additional push from a
diurnally-developing lake breeze and begin to march farther
inland late this afternoon and especially this evening.
Temperature trends in the vicinity of the lake are a bit
uncertain today given some notable timing differences with the
handling of the eventual secondary lake breeze push. That said,
high temperatures at the immediate lakefront will likely hold in
the 50s while areas south of I-80 appear set to rise well into
the 70s and even lower 80s through the afternoon.

Deeper boundary layer moisture will reside across parts of
northwest Indiana later this morning and afternoon. Forecast
soundings look quite capped through the morning, but MLCIN is
eventually forecast to erode as temperatures warm. While large
scale forcing looks somewhat weak, general troughing is forecast
to be present across our northwest Indiana locales this
afternoon as a modest 700 mb shortwave scoots out of eastern
Iowa. This, coupled with increased low-level convergence along
the inland-moving lake breeze/front within a moist boundary
layer may support the potential for isolated to perhaps widely
scattered convection during peak heating. Have maintained some
20-30 percent PoPs generally south of I-80 and east of I-57 for
this. With the deepest BL moisture and forcing forecast to
remain just east of our region, expect the highest coverage of
storms to focus across north central and northeast Indiana. If
more robust convective development materializes, storm motions
would likely be quite slow, with an associated potential for
very localized heavy rainfall. This signal is not ubiquitous
across the high-res suite, but at least a smattering of
guidance points to this potential for an anchored storm of two
getting close to our far southeast late in the day and early
evening. Finally, can`t rule out the potential for a funnel
cloud in this environment, characterized by steepening 0-1 km
lapse rates, increasing 0-3 km MLCAPE, fairly low deep layer
shear, and the presence of enhanced vertical vorticity near a
surface boundary.

While some activity could linger through the evening, we should
trend precip-free during the overnight. Some guidance now wants
to push some lake stratus/fog inland into early Thursday
morning, but with the low-level flow turning offshore, have not
included a fog mention over land at this point, but may need to
do so in future updates if trends continue. Very warm and breezy
conditions will develop on Thursday ahead of the next cold
front. Temperatures appear likely to push towards 80 across a
broad swath of the area, and potentially into the mid 80s closer
to central Illinois.

Showers and thunderstorms will develop well to our west through
Thursday afternoon on a cold front and will then track eastward
into our area either very late Thursday night or Friday morning.
The instability/shear parameter space remains unimpressive
locally. The severe threat continues to appear low in our area.
Showers and some storms will probably linger into the afternoon
before the cold front sweeps through the area. More seasonable
conditions will occur over the weekend with temperatures in the
60s/lower 70s (and cooler temperatures near the lake). Another
storm system will approach the area towards the Monday-Monday
night timeframe. Lots of variability with this one as this will
involve a broad trough ejection across the Great Basin.
Depending on the timing and location of the attendant surface
low, there could be a strong-severe threat with this, but model
spread is too high to have any confidence in a particular
solution at this point.

Carlaw

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 632 AM CDT Wed Apr 22 2026

Key messages for the 12Z TAF period:

* Possible few hour period of MVFR cigs this morning.

* Low confidence potential for additional fog/low stratus
  impacts tonight into early Thursday.

Winds largely below 10 kt this morning will veer from SW to NW,
then onto NE behind a passing cold front. Timing on this NE
shift is somewhat uncertain and has been trending later into the
morning, now looking like around 17Z at Chicago. Expect light
SE`erlies tonight going SSW by early Thursday and building with
gusts to around 20 kt by mid-late morning.

While the signal for any impacts this morning with this passing
front has waned considerably over the past 12-24 hours, there
remains a possibility for a few hour period of MVFR cigs mid-
late morning around Chicagoland.

Another potential exists for additional impacts due to fog and
low stratus this evening into early Thursday. There is low
confidence surrounding this signal with the highest impacts
anticipated near Lake Michigan. Accordingly, maintained low VFR
conditions around Chicagoland, but watch this period for cat
changes in future forecasts.

Doom

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

Visit us at weather.gov/chicago